Bicycles have front and rear chain rings about which a bicycle chain passes. The rear chain ring can be a single ring or a number of axially spaced rings of different diameters, thereby allowing various speed ratios to be obtained. The front chain ring is attached to a crank with the crank being attached to pedals. Rotation of the crank causes the chain ring to rotate.
With certain bicycles, and especially mountain bikes, there is a possibility that the chain becomes dislodged from the front chain ring, especially when rough riding. Rough riding causes the chain to rattle and move and there is an increased possibility that the chain can become suddenly dislodged from the chain ring. This can result in injury to the rider, and requires the chain to be re-positioned before further riding can take place.
Guides to guide and assist in maintaining the chain in engagement with the front chain ring are known. Typically, the guides consist of a first upper guide which is adjacent where the chain initially engages the chain ring, and a second bottom guide which is positioned adjacent where the chain disengages from the chain ring. While these guides are already known, the principle disadvantage with them is that they are attached directly to the bicycle frame. The guides need to be precisely positioned to work properly, and therefore there is a high skill required in attaching the guides to the bicycle frame.
This becomes difficult with the hundreds of different frame designs and dimensions. It is found that certain frame designs cannot easily provide a support for the guides. It is also found that a great number of adjustments are required to position the guides effectively. It is also found that modification of existing guides is required to position the guides effectively.